|Year : 2015 | Volume
| Issue : 2 | Page : 89-93
Assessment of serum trace metals and body mass indices in rural and urban healthy adult population: A pilot study
Pavana Sreenivasan1, Akila Prashant2, Suma M Nataraj2, Prashant Vishwanath2, Saket Verma2, Swetha Chandru3
1 MBBS Student, JSS Medical College, JSS University, Mysore, India
2 Department of Biochemistry, JSS Medical College, JSS University, Mysore, India
3 Department of Biochemistry, MVJ Medical College and Research Hospital, Hoskote, Karnataka, India
|Date of Web Publication||10-Apr-2015|
Department of Biochemistry, JSS Medical College, JSS University, Mysore, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Limited community-based data are available on the serum zinc and copper levels and factors affecting their levels in the adult healthy population of rural and urban India. Hence, the present study is conducted to evaluate and compare the serum levels of zinc and copper with body mass indices (BMI) in rural and urban healthy adult population. Materials and Methods: Fifty subjects each from the rural and urban population in the age group of 20-40 years were recruited for the study. Subjects having past medical histories of major diseases and with acute infections were excluded. Their anthropometric measurements such as height, weight, hip, and waist circumference were measured, and the BMI calculated. Venous samples collected from them were used to determine the levels of zinc and copper. Results: Both the subject groups had optimum levels of zinc, but the urban subjects were deficient in copper. The levels of serum zinc were higher in the urban population while the levels of copper were higher in the rural population. In addition, the levels of serum zinc and copper were negatively correlated with each other but were not statistically significant. Considering each of the population individually, there was no gender wise difference between the serum zinc and copper levels and were almost the same. The BMI had a strong positive correlation with the serum zinc levels in the rural population (P = 0.026). However, it did not have any correlation with the copper levels. Conclusion: Our study brought out the association between serum zinc levels and BMI and the fact that serum zinc levels were higher in the urban population and copper levels in the rural population. Emphasis on the diet rich in these trace elements can help in maintaining adequate and balanced levels of zinc and copper.
Keywords: Rural population, serum copper, serum zinc, urban population
|How to cite this article:|
Sreenivasan P, Prashant A, Nataraj SM, Vishwanath P, Verma S, Chandru S. Assessment of serum trace metals and body mass indices in rural and urban healthy adult population: A pilot study. Int J Health Allied Sci 2015;4:89-93
|How to cite this URL:|
Sreenivasan P, Prashant A, Nataraj SM, Vishwanath P, Verma S, Chandru S. Assessment of serum trace metals and body mass indices in rural and urban healthy adult population: A pilot study. Int J Health Allied Sci [serial online] 2015 [cited 2022 Oct 5];4:89-93. Available from: https://www.ijhas.in/text.asp?2015/4/2/89/153612
| Introduction|| |
Zinc is one of the most abundant trace elements in the body. It mediates several vital physiological functions and is essential for maintaining a healthy immune system and meeting metabolic demands. Zinc deficiency is a major public health problem in South East Asia with nearly 95% of the population being at risk due to low dietary zinc intake.  Copper is essential in normal cell metabolism and is present in all cells and tissues.  Both are involved in many biochemical processes supporting life like cellular respiration, cellular utilization of oxygen, DNA and RNA reproduction, maintenance of the cell membrane integrity, and sequestration of free radicals. Copper and zinc are also involved in the destruction of free radicals through cascading enzyme systems. On the other hand, excess intake of these trace elements leads to disease and toxicity; therefore, a fine balance is essential for health. Trace element-deficient patients usually present with common symptoms such as malaise, loss of appetite, anemia, infection, skin lesions, and low-grade neuropathy, thus complicating the diagnosis. Symptoms for intoxication by trace elements are general, for example, flu-like and central nervous system symptoms, fever, coughing, nausea, vomiting, diarrhea, anemia, and neuropathy. 
Limited community-based data are available on the serum zinc and copper levels and factors affecting their levels in the adult healthy population of rural and urban India. Furthermore, dietary intake of zinc and copper by a population of low-income groups in India has been found to be low, probably because of the low bioavailability of these micronutrients in the Indian soil.  Hence, the present study is conducted to evaluate and compare the serum levels of copper and zinc with body mass indices (BMI) in rural and urban healthy adult population.
| Materials and methods|| |
Fifty subjects each from rural and urban population of Mysore city were recruited at random. Institutional Ethical Committee clearance was taken before the commencement of the study. Individual written consent was obtained from the subjects before collecting the data and blood sample for the study purpose.
Healthy adult subjects in the age group of 20-40 years without any underlying disease from the rural and urban population of Mysore were included in the study.
According to census of India 2011, the area which fulfilled the following criteria was identified as a rural area:
- The area under the jurisdiction of a panchayat or
- A place satisfying the following three criteria simultaneously:
- Total population of <5000
- At least 75% of male working population engaged in agricultural pursuits; and
- A density of population of <400/km 2 (1000/mile 2 ).
The area which did not fulfill the above criteria was classified as an urban area.
Past medical histories of any major disease (malignancy, cardiac disease, connective tissue disease, and gastrointestinal disease including malabsorption) and subjects having any acute infections were excluded from the study.
About 3 ml of venous blood was collected from about 50 rural and 50 urban healthy adult population using aseptic precautions. At the same time, the data regarding their age, occupation, socioeconomic status, history of diabetes and hypertension, and their hemoglobin levels were noted in a preformed proforma. A detailed information regarding their dietary habits like the type of food consumed, frequency of consumption of nonvegetarian diet, the mode and type of utensils used for cooking were noted. The source of water and the process of water purification technique were also enquired.
For all patients, anthropometric parameters including: Weight, height, hip, and waist circumference were measured. Calculated BMI was used to classify individuals into underweight (BMI < 18 kg/m 2 ), normal weight (18-24.9 kg/m 2 ), overweight (25-29.9 kg/m 2 ), and obese (>30 kg/m 2 ) groups. 
Serum zinc and copper analysis
Blood samples were centrifuged after 30 min, and the separated serum was used for the estimation of serum zinc and copper. Zinc was estimated by colorimetric method. Zinc present in the sample was chelated by 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N- sulfopropylamino)-phenol in the reagent. The formation of this complex was measured at a wavelength of 560 nm. At pH 4.7, copper which was bound to Ceruloplasmin is released by a reducing agent. It then reacted with a specific color reagent, 4-(3,5-Dibromo-2-pyridylazo)-N-Ethyl-N-(3-sulphopropyl) aniline, to form a stable, colored chelate. The intensity of the color is directly proportional to the amount of copper in the sample. Both zinc and copper estimations were performed with the kits available from Randox laboratories which were programmed, calibrated, and performed on a fully automated RANDOX daytona analyzer, and quality control was performed as per specifications. 
The reference ranges for the serum zinc and copper were taken as follows: ,,
- Copper: Men: 10.99-21.98 (μmol/L); women:
- Zinc: 10.7-18.4 (μmol/L) for both men and women.
The data were subjected to statistical evaluation, using MedCalc 220.127.116.11 software packages, with descriptive statistics (mean, median, standard deviation, and interquartile range) being determined for all variables. Data for groups and subgroups were compared using t-tests and Chi-square tests were used for quantitative and qualitative variables using a Bonferonni correction for multiple comparisons. Analysis of covariance was used to assess differences after adjustment for important confounding factors including age, gender, smoking habit, blood pressure, fasting blood sugar, lipid profile, and BMI.
| Results|| |
The serum zinc and copper levels in the urban and rural population are shown in [Table 1]. The serum zinc levels were higher in the urban population when compared with the rural population. Serum copper levels were higher in the rural population when compared to the urban population. The sex wise difference of serum zinc and serum copper levels in the urban population is shown in [Table 2]. It is seen that in the urban population, there was no significant difference in the serum zinc and copper levels between males and females. The sex wise difference of serum zinc and serum copper levels in the rural population is shown in [Table 3]. It is seen that in the rural population too there was no significant difference in the serum zinc and copper levels between males and females.
|Table 2: Sex wise difference in serum zinc and copper levels in urban population|
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|Table 3: Sex wise difference in serum zinc and serum copper levels in rural population|
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Correlation between serum zinc and copper levels in a rural population is shown in [Figure 1]. It is seen that there is a mild negative correlation between serum zinc and copper levels in the rural population. However, it is not statistically significant (P = 0.087). Correlation between serum zinc and copper levels in urban population is shown in [Figure 2]. It is seen that there is a negative correlation between serum zinc and copper levels in the urban population. However, this is also not statistically significant (P = 0.111). The correlation of BMI with serum copper and zinc in the urban and rural population is shown in [Table 4]. There was no significant correlation of BMI with serum zinc or copper levels in the urban population. However, in the rural population, BMI showed a negative correlation with serum copper (statistically not significant P = 0.210) and significant positive correlation with serum zinc (P = 0.026).
|Figure 1: Correlation between serum zinc and copper levels in rural population|
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|Figure 2: Correlation between serum zinc and copper levels in urban population|
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Hence, on comparing the serum levels of copper and zinc with the BMI, it was found that a moderate correlation exists between these micronutrients and BMI.
| Discussion|| |
The main source of zinc and copper is through diet. Hence, consuming diet rich in zinc and copper helps in elevating their levels. This includes meat, fish, eggs, milk, beans, and nuts for zinc and egg yolk, cereals, green leafy vegetables, liver, kidney, and nuts for copper. 
On assessing the levels of serum zinc and copper in comparison with the normal range, it was found that both the rural and urban subjects had optimum levels of zinc, but the urban subjects were deficient in copper. This could be attributed to decreased consumption of green leafy vegetables by the urban subjects as per the dietary history noted in the study proforma. Green leafy vegetables have phytate content in them which aids in copper absorption and decreases zinc absorption, on the other hand. ,
On comparing and assessing the levels of serum zinc in urban and rural population, it is shown to be higher among the urban subjects. A lot of factors could be illustrated for this. As diet is known to play a major factor for these levels, urban population consumed diet rich in meat, liver, and eggs in a higher frequency (almost every day) when compared to the rural subjects (about once in 2 weeks). In addition to this, the urban subjects were consuming diet deficient in green leafy vegetables thus providing no hindrance in the absorption of zinc.
Furthermore, rural population utilized copper utensils for cooking their food whereas it was not used by the urban population. Another important contributing factor is water purification at purification plants present mostly in urban areas and also portable water purification systems available commercially to purify water at household level in urban areas which filters trace elements along with other contaminants. These water purification systems were not available in a rural population. The decreased levels of zinc in the rural population could be explained by the fact that their nourishment status when compared with the urban population was poorer. Stress was another major factor that was present in them which could reduce the zinc levels.  In addition to all this, the high levels of copper in the rural population in comparison with the urban subjects also play a role in reducing the zinc levels.
The copper levels were known to be almost twice higher in the rural subjects when compared to the urban subjects. They are known to consume a diet rich in green leafy vegetables and cereals. These are rich in copper. They also, as mentioned above, consumed lesser amount of meat compared to the urban subjects. While comparing the lifestyles between the two subjects, was found that the rural subjects store, cook, and eat food in copper vessels which adds on to the regular diet. In the subjects taken for the study, it was observed that many rural subjects are known to smoke in comparison with the urban subjects. This decreases the zinc levels and raises the copper levels in their serum.
When each of the population was considered separately, and the levels of zinc and copper were assessed amongst males and females, it was found that they were almost similar. The dietary habits, lifestyle, and the residence were almost the same considering the individual population. Hence, the levels could not have changed much unless there was another factor playing a role which was not the case in this study.
The BMI of urban and rural population was within the normal range. However, on comparing the BMI with serum zinc levels, there was a statistically significant positive correlation between the two. Most of the zinc in the serum is bound to albumin.  So when there is a decrease in serum albumin (as in malnourished states), the levels of zinc in the serum fall too. Hence, a well-nourished state is required to maintain adequate zinc levels. Nourishment of a body is assessed based on the BMI (which is calculated by weight [kg]/height [m 2 ]). Therefore, zinc levels and the BMI are directly proportional to each other.
The levels of serum zinc and serum copper are inversely related, that is, as an increase in absorption or increased levels in one ultimately causes decreased levels and decreased absorption of the other. Therefore, the optimum balance between the levels of zinc and copper is required to be maintained. The manifestations of the imbalance between the two levels end up complicating the diagnosis. Separately, zinc and copper serve as an important biomarker marker for the diagnosis and monitoring the prognosis of several diseases. ,
Apart from incorporating them in the multivitamin supplements, administering them in hospitalized patients have proven to be helpful; for instance, the need for administering zinc in patients suffering from diarrhea and pneumonia. , Other methods that can be useful are food fortification to beverages or condiments, genetic modification of plants to increase their level of absorbable zinc, implication of zinc supplementation especially for high-risk population, , household intervention for increasing the zinc content by reducing the phytate content of diets, that is, germination to increase phytase activity, fermentation to increase microbial phytase activity, and soaking to reduce phytic acid content, and finally using natural and artificial fertilizers in areas where zinc content of the soil is very low.  Furthermore, it seems that comprehensive studies are required to be designed to determine a precise cut-off point for estimation of the prevalence of zinc and copper deficiency in our country so that an appropriate guidance can be established for this issue.
Limitations of the study
Small sample size is the limitation of the study and hence intra-group comparisons could not be made. However, this can be taken as the preliminary data to design a large scale multicentric study.
| Conclusion|| |
The health and disease pattern in the urban and rural population differs even at the local regional level. At present, there is little information available on factors affecting the serum trace metal levels. The study of the serum trace metals and certain physical factors like BMI and other anthropometric indices can provide useful information about the risk factors in the urban and rural population. Multicentric studies will also allow us to obtain reference values of serum zinc and copper for the adult healthy group of Indian population, which will serve as a baseline for a comparative study with groups having pathological conditions.
| Acknowledgment|| |
This study was done as a part of ICMR-STS 2013.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]